The 39th Wetland Bird Survey (WeBS) for 2019/20 has been published, Simon Wotton, Senior Conservation Scientist, highlights the key findings from the report.

WeBS is the principal scheme for monitoring the populations of the UK's wintering waterbirds, providing an important indicator of the status of waterbird populations and the health of wetlands.  The survey is run by the British Trust for Ornithology (BTO), in a partnership between the BTO, RSPB and the Joint Nature Conservation Committee (JNCC), in association with the Wildfowl & Wetlands Trust (WWT).

WeBS aims to assess the size of waterbird populations, determine trends in numbers and distribution, and assess the importance of individual sites. The 2019/20 report documents waterbird counts at 2,946 sites across the UK, surveyed by 3,450 WeBS counters. The 2019/20 WeBS year was a challenging one, with counting affected by Storm Ciara in February 2020 and COVID-19 pandemic restrictions limiting surveying from March.

Thousands of knot circling at RSPB Snettisham, part of the Wash, a site of international importance for waterbirds © Kelly Thomas (rspb-images.com)

Significant sites

Many of the sites monitored under WeBS are of international importance and designated as Ramsar Sites and Special Protection Areas (SPAs), including the four principal WeBS sites over the past five years: The Wash, the Ribble Estuary, Morecambe Bay and the Dee Estuary. 

The Wash remains the most important site for wintering waterbirds in the UK, with 422,232 birds counted in 2019/20 (417,911 in 2018/19), followed by the Ribble Estuary with 201,883 waterbirds counted (235,780 in 2018/19). Winter temperatures were much milder than normal in the Baltic, and for Europe as a whole the winter was the warmest on record.

Many migratory species were present in low numbers, especially those wildfowl species that could take advantage of a record warm winter for Europe and mild temperatures in the Baltic Sea to avoid a longer migration to the UK.

Impact on species

Bewick’s Swan, taiga bean goose and Icelandic greylag goose all declined year-on-year and have declining trends over the past 10 and 25 years. European white-fronted goose numbers were slightly up on the previous year but have declined by 70% since 1993/94.

European white-fronted goose © Andy Hay (rspb-images.com)

The number of scaup wintering in the UK has declined by three quarters since the peak in 1973/74. At the same time, scaup counts in the winter have increased in northern and eastern Europe. Britain and Ireland were an important wintering area for this northern-breeding seaduck, but during the last 50 years overwinter numbers have been falling.

Goldeneye and Bewick’s swans from the northwest European breeding population are also remaining on the other side of the North Sea in increasing numbers during the winter months - these species declined by 58% and 88% respectively between the winters of 1993/94 and 2018/19.

Surprisingly perhaps, given its ubiquity during the breeding season, the number of coots that winter in the UK has also fallen, down by 15% over the same period. Results from the International Waterbird Census and International Swan Census, which WeBS feeds into for the UK, give the bigger picture for the population declines being seen here.

Whereas the European populations of coot and goldeneye appear to be stable overall and the observed changes are due to redistribution of wintering areas, the breeding populations of scaup and Bewick’s swan have declined, as well as experiencing changes in their winter distribution. 

Scaup have declined by three quarters © Tom Benson (Flickr - CC BY-NC-ND 2.0)

Common waterbirds

Many of the common wintering wader species are declining, with only avocet, black-tailed godwit and sanderling showing long-term increases. The latest index values were lower than 2018/19 for declining species oystercatcher, lapwing, grey plover, bar-tailed godwit (record low), dunlin (record low), purple sandpiper (record low) and redshank.

Sanderling had a notably low index value after two high years. Golden plover, ringed plover, curlew, turnstone and knot all saw higher winter numbers than the previous year, notwithstanding negative 10-year and 25-year trends.

Detailed data on WeBS sites and species are available through the BTO WeBS interactive website. A copy of the 2019/20 report can be downloaded here.

For more information contact Simon Wotton, Senior Conservation Scientist, or Ness Amaral-Rogers, Science Communications Executive, or follow us on Twitter @RSPBScience #WeBS #wetlandbirds.

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